[PATCH v2 2/2] ARM: move device tree mapping out of linear region

[Russell King - ARM Linux admin]

On Wed, Oct 28, 2020 at 02:04:41PM +0100, Ard Biesheuvel wrote:
> On Wed, 28 Oct 2020 at 14:01, Russell King - ARM Linux admin
> <linux at armlinux.org.uk> wrote:
> >
> > On Wed, Oct 28, 2020 at 01:52:48PM +0100, Ard Biesheuvel wrote:
> > > Does this help?
> > >
> > > diff --git a/arch/arm/include/asm/memory.h b/arch/arm/include/asm/memory.h
> > > index bb79e52aeb90..4f355bda872a 100644
> > > --- a/arch/arm/include/asm/memory.h
> > > +++ b/arch/arm/include/asm/memory.h
> > > @@ -68,8 +68,8 @@
> > >  #define XIP_VIRT_ADDR(physaddr)  (MODULES_VADDR + ((physaddr) & 0x000fffff))
> > >
> > >  #define FDT_FIXED_BASE         UL(0xff800000)
> > > -#define FDT_FIXED_SIZE         (2 * PMD_SIZE)
> > > -#define FDT_VIRT_ADDR(physaddr)        ((void *)(FDT_FIXED_BASE |
> > > (physaddr) % PMD_SIZE))
> > > +#define FDT_FIXED_SIZE         (2 * SECTION_SIZE)
> > > +#define FDT_VIRT_ADDR(physaddr)        ((void *)(FDT_FIXED_BASE |
> > > (physaddr) % SECTION_SIZE))
> >
> > Is this correct? If the FDT fixed size is 2x, why does FDT_VIRT_ADDR()
> > only work for half of it?
> >
> 
> Perhaps the naming is confusing. This is only used to obtain the start
> of the virtually mapped DT, which amounts to the virtual address of
> the section plus the physical address modulo the section size.
> 
> I will rename physaddr to physbase when I respin this as a patch.
> Shall I rename FDT_VIRT_ADDR to FDT_VIRT_BASE as well?

Yes please, I think that makes it clearer what is going on here.

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